The present invention relates to compositions and methods useful in reliably sealing, patching or closing a hole or opening in a workpiece such as a vehicle body. Further, the compositions and methods are particularly useful in reliably sealing, patching or closing a drain hole in an automobile body panel or the like.
In many industrial coating or treating processes, workpieces are submerged or immersed in a treatment/coating bath or solution. Such techniques provide excellent control over treatment times and allow uniform surface treatment of ordinarily inaccessible areas of the workpiece. However, removing or draining the bath or solution from the workpiece frequently requires the deliberate drilling, boring or forming of holes in the workpiece to allow prompt and controlled drainage.
For example, vehicles bodies are frequently immersed in tanks to effect a phosphate conversion coating which serves to inhibit surface oxidation and to provide a paint base. However, due to the configuration of such a workpiece, drainage of the treatment solution would be extremely difficult without the "drainage holes" that are provided to allow the solution to freely drain from the workpiece.
It will be appreciated, however, that after treatment and drainage such holes serve no useful purpose and, in fact, can create problems in later manufacturing or processing operations or steps; such holes can also be extremely detrimental to the appearance or integrity of the final product. Accordingly, it is highly desirable to seal or plug these drainage holes after the immersion and drainage steps are completed.
Most automobile drain and gauge hole covers are sealed by placing an expandable thermoplastic hot melt sealant-gasket around the edges of the cover. The sealant is softened, expanded and flowed by heat from the paint ovens. The paint ovens range in temperature from a low of 15 minutes at 230.degree. F. to a high of 30 minutes at approximately 315.degree. F.
Many efforts have been made to provide a satisfactory seal. For example, U.S. Pat. No. 4,494,671, issued Jan. 22, 1985, discloses a closure for such a hole in a panel which includes:
(a) a plate; PA1 (b) a gasket; PA1 (c) means for securing said gasket to said plate; and PA1 (d) means for securing said plate to the panel.
The gasket is disclosed as having a thin, bottom side "low melt" compound which forms the seal when heated.
U.S. Pat. No. 3,851,794, issued Dec. 3, 1974, discloses a method of sealing a varnish exit hole in a work panel by means of a plug inserted into the hole. The plug has a closed bottom wall, a head superimposing the margins of the work panel and an annular collar joining the bottom wall to the head.
U.S. Pat. No. 4,147,576, issued Apr. 3, 1979, discloses a kit and method for repairing vehicle surfaces. In this method the surface to be repaired is covered by adhering a plastic sheet having beveled edges to the repair surface. This is followed by the step of sanding the beveled edges and adhering sealant to at least the visible edges of the repair surface. Next, it is suggested that there be a feathering of the sealant to create a smooth surface. Lastly, the repaired area is painted. The adhesives employed include a contact cement.
U.S. Pat. No. 4,290,536, issued Sept. 22, 1981, discloses a second type of sealing plug device for fitting holes in panels. These plastic plugs are made to include a thermofusible material which surrounds the plastic plug as a bead. After being put in position, the plug is treated so that the thermofusible ring melts to fill an empty space around the plug to seal the hole.
U.S. Pat. No. 4,430,133, issued Feb. 7, 1984 discloses a process for replacing damaged parts of a vehicle. In summary, the process includes placing a manufactured overdimensioned acrylic part over the damaged part and adhering this overdimensioned part to the damaged part.
U.S. Pat. No. 4,486,254, issued Dec. 4, 1984, discloses a heat-activated patch or repair composition for metal objects or surfaces. The composition contains silicate, soda and asbestos fiberous cement and lesser amounts of iron ore and an alumina-containing air set mortar. The heat-activated composition is employed in conjunction with an asbestos cloth, such as woven asbestos cloth, to provide a comparatively permanent patch or repair of a metal object and surface.